Various types of hose clamps are known in the prior art in which a clamping band made of flat strip material was adapted to be mechanically interconnected at the free ends thereof to form a ring-like clamping structure that can be tightened by contraction of so-called "Oetiker" ear as described in U.S. Pat. No. 3,789,463.
In particular, U.S. Pat. No. 4,299,012 discloses a clamping band having open ends adapted to be mechanically interconnected by outwardly extending hooks in an inner band portion operable to engage in corresponding apertures provided in an outer band portion. The band is provided with a plastically deformable ear which is provided for tightening the clamping band about an object to be fastened by plastic deformation of the ear. This clamp provides a substantially gap-free transition in the circumferential direction from the inner band portion to the ring like configuration of the clamp structured defined by the clamping band by the use of a tongue like extension at the free end of the inner band portion which is operable to engage into a tongue receiving aperture or channel provided in the outer band portion.
In order to provide the hooks of this type of clamp with sufficient strength to resist the tensional forces upon contracting the ear, the clamp is provided with at least one support hook which is realised by cold-deforming the band material to present a force engaging abutment surface to absorb the circumferentially directed forces. Although the cold deformed support hooks resist the circumferentially directed forces adequately, such support hooks do not adequately engage the aperture in the outer band member to maintain engagement therewith during crimping of the ear. As a result, the outer band member may dislodge from the inner band member during contraction of the ear resulting in the misclamping of the clamp about the objects to be clamped. This results in waste as the clamps cannot be reused after the ear has been deformed.
A person installing a clamp could deform the ear in a manner known in the art until the outer band member on opposite sides of the ear contact each other for maximum clamping force. Other than maximum clamping where the ear is fully deformed, there is no way to determine accurately the degree of clamping force which has been applied to the hose. There is no reliable method for determining whether the clamp has been crimped to a sufficient degree. Quality control of the installation of such clamps is difficult, time consuming and requires a special skill to evaluate the crimp of the clamp.